Communication system for railway yards



April 26, 1938. R, R KEMMERER 2,115,583

COMMUNICATION SYSTEM FOR RAILWAY YARDS Filed March 4, 1957 HIS ATTORNEY Patented Apr. 26, 1938 UNITED STATES PATENT OFFICE Ralph R. Kemmerer, Swissvale, Pa., assigner to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application March 4, 1937, Serial No. 129,021

13 Claims.

My invention relates to communication systems for railway yards.

A feature of my invention is the provision of apparatus for communication from any one of a plurality of control stations located about a railway yard toa vehicle such as, for example, a shifting locomotive on any yard track. A further feature of my invention is the provision of apparatus for communication systems of the type here contemplated which operates on the closed circuit principle. A still further feature of my invention is the provision of apparatus for systems of the type here involved to indicate ateach control station that the system is in Working order, and to also indicate at each station when the apparatus at that station is conditioned for sending and when communication is in progress from one of the other control stations. Other features and advantages of my invention will appear as the specification progresses.

I will describe one form of apparatus embodying my invention, and will then point out the novel features thereof in claims.

Referring to the drawing, Fig. 1 is a diagrammatic View of one form of apparatus embodying my invention when applied to a receiving yard leading to a hump track, and along which track two control stations are located. Fig. 2 is a diagrammatic View of the apparatus and circuitsl -provided at the control stations of Fig. 1 for governing the transmitting apparatus thereof. In each of the two views, similar reference characters designate similar parts.

My invention is especially useful for directing the movements of shifting locomotives in classification yards where a hump is used. It will be understood that the invention is not limited to this one application and many places for its use will suggest themselves. This one embodiment v of the invention will serve, however, to illustrate the many places where the invention is useful.

Referring to Fig. l, the reference character RY designates a receiving yard which, as here shown, comprises three parallel tracks IT, 2T and A. 3T. Traffic normally enters the yard RY from a `main track (not shown) to the right, as viewed in Fig. l. Traffic leaves the yard RY over a hump track HT, and from thence it moves into .a classication yard (not shown) to the left of Fig. 1. In accordance with the usual practice, cars are collected on the several tracks of the receiving yard RY and are then pushed over the hump by a shifting locomotive, the movement of the cars from the hump to the classification yard being governed by car retarders or car riders, as desired.

The usual track scale may also be provided in the hump track HT. Although only three tracks are shown in the yard RY, it will be understood that the yard may be provided with additional tracks, each of which is connected with the hump track by the customary ladder track.

The purpose of the present invention is to enable operators stationed at the control points along the hump track to communicate with the crew in the cab of a shifting locomotive on any one of the tracks of the receiving yard for directing the movement of the locomotive in pushextends through the receiving yard over the track rails of the several tracks in multiple to a point D along the hump track Where a wire is connected to each rail of the hump track in the usual manner, and the circuit is then completed over wire 5 which is connected with the lower right-hand output terminal of the transmitting apparatus TA. 3

The track rails may be bonded by the usual rail bonds to improve their electrical conductivity, but they need not be insulated into track sections by the customary insulating rail joints. This transmitting circuit is intended for cooperation with vehicle carried apparatus responsive to alternating current flowing in the rails, energy being preferably transferred from the track rails to the vehicle carried apparatus inductively through the medium of an inductor mounted on the vehicle in inductive relation with the track rails. It will be observed that the transmitting circuit is not shunted by the wheels and axles of a vehicle, and the rails of each track form a branch path in the transmitting circuit so that energy will be transferred to a vehicle provided with such receiving apparatus irrespective of the track occupied by the vehicle, whether the inductor is at one end or the other of the vehicle, whether the vehicle is proceeded o1' followed by other vehicles on the same track, and whether the other tracks are occupied by other cars.

The structure of the vehicle carried receiving apparatus. is immaterial and may be receiving apparatus of the type disclosed in the United States application for Letters Patent Serial No. 133,214, led March 26, 1937 by Willard P. Place for Receiving apparatus for communication systems. Such vehicle carried receiving apparatus is normally conditioned for reception and is responsive to a carrier signaling current of a predetermined frequency for governing a cab indicator, and is conditioned for reception of a carrier telephone current when the signaling current'is discontinued, the voice frequencies of such carrier telephone current being reproduced at a loud speaker or telephone receiver. The cab indicator, when displayed, indicates that the transmitting circuit is energized with signaling current and the circuit is in working order for transmission of the telephone current. The cab indicator, when extinguished, indicates that the signaling current is discontinued, due either to a failure of the system or that an operator at a wayside station is about to initiate telephone communication. It is clear that such vehicle carried receiving apparatus may be used for signaling as well as for telephone communication, the cab indicator, when illuminated, being a signal for the shifting locomotive to proceed in pushing cars over the hump and, when extinguished, being a signal for the locomotive to stop unless the extinguishing of the indicator is immediately followed by Verbal instructions. In the present invention, one-way communication only is contemplated and the vehicle is not provided with transmitting apparatus.

The transmitting apparatusl TA would be located at any convenient point and preferably would be mounted in suitable housing in the vicinity of the point D. The transmitting apparatus TA may be any one of several well-known types and will be referred to more fully hereinafter.

Two control stations SI and S2 are located along the hump track HT at desired points such as, for example, the yard oce and the track scales. As here shown, these control stations are spaced apart and are remote from the transmitting apparatus TA. For the purpose `of enabling operato-rs stationed at the control stations SI and S2 to communicate with the crew of a shifting locomotive in the yard RY through the medium of the transmitting circuit, these stations are each provided with control apparatus` to be described later, which is connected with the transmitting apparatus TA over line circuits indicated as a whole by the reference character L irl-Fig. l. Although only two control stations are provided, it will be understood the invention is not limited to two control stations, and other stations may be established at other points, as desired.

Referring to Fig. 2, the transmitting apparatus TA comprises a modulator-oscillator MO, an amplifier AM, an output transformer TI and an input transformerV T2. The modulator-oscillator MO and the amplifier AM may each be any one of several well-known types for such devices, and are shown conventionally only for the sake of simplicity, since the specific structure of each such device forms no part of my present invention. The modulator-oscillator MO and the amplifier AM may be of the type disclosed in the United States Letters Patent No. 2,064,639, granted December l5, 1936, to Whitelock et al. for Communication systems. It is believed to be sufficient for the instant application to point out that the modulator-oscillator MO includes an oscillator or generator of carrier frequency current and means for modulating such carrier current by voice frequencies. The modulator-oscillator MO is also provided with circuit means Wherevvith the original carrier frequency may be shifted a few cycles up or down to produce a signaling current, such signaling current being the equivalent of the original carrier modulated by a predetermined voice frequency. This circuit means is such that when a control relay RI is energized to close its front contact I0 the capacitance or inductance of the associated oscillating circuit is varied andl the carrier frequency is shifted, but when the relay RI is deenergized and released to open the front contact Ii! carrier current of the original frequency is generated. A voice frequency current supplied to the primary winding II of the input transformer T2, in a manner later to appear, induces electromotive forces of like frequencies in the secondary winding I2 of the transformer T2, and these electromotive forces are applied to the input side of the modulator-oscillator for modulating the carrier current. The output side of the modulatoroscillator is connected over wires 6 and 'I to the input side of the amplifier AM, which may be two electron tubes connected in the usual push-pull arrangement; The output side of the amplifier AM is connected with the primary winding 8 of the output transformer TI, the secondary Winding 9 of which is connected to the wires 4 and 5 of the transmitting circuit traced hereinbefore. It follows that normally, that is, when relay RI is energized and its front contact II) is closed, the transmitting apparatus TA is operative to supply the transmitting circuit with a signaling current of a predetermined frequency, but that when relay RI is released and its front contact Iii is opened the transmitting apparatus is conditioned for supplying the transmitting circuit with a carrier telephone current resulting from modulation of the carrier by voice frequencies supplied to the input transformer T2.

'Ihe control stations SI and S2 are each provided with control apparatus which includes, in each case, a push button type circuit controller and two indication lamps as well as a microphone. The push buttons PBI and PBZ at the stations SI and S2, respectively, are of the spring return type and carry normally closed contacts as Well as contacts closed when the push button is depressed. The indication lamps Li and L2 at the stations SI and S2, respectively, when illuminated, indicate that the relay RI is energized to condition the transmitting apparatus for sup'- plying the transmitting circuit with the signaling current, and hence indicate to the operators at these stations that the system is in working order. 'I'he lamp LAI at station SI, when illuminated, indicates that the circuit for the associated microphone MI is effective. Likewise, the lamp LA2 at station S2, when illuminated, indicates that the circuit of the associated microphone M2 is eiective. The indication lamps at each control station also indicate when communication is in progress at the other control station.

When the push buttons PBI and PB2 are normal, that is, in the position illustrated in Fig. 2, a circuit is completed from the B terminal of any convenient source, such as a battery not shown, over normally closed contact I3 of push button PBI, wire I4, normally closed contact I5 of push button FB2, line wire I6, winding of relay RI and to the C terminal of the same source of current, and the relay RI is energized. With relay RI picked up to close front contact I 0, the trans- 76- mitting apparatus TA is conditioned for supplying signaling current in the manner described hereinbefore. The closing of iront contact I'I of relay RI completes a circuit for the lamps LI and L2, and which circuit may be traced from the B terminal of the current source over normally closed contact I3 of push button PBI, wire: I4, normally closed contact I5 of push button PB2, Wire I6 to wire 25, and thence through lamp L2 at station S2 to line Wire I8, or through lamp LI at station SI to wire I8, front contact I1 of relay RI and to the C terminal, and the two lamps LI and L2 are illuminated in parallel. Consequently, under the normal condition of the system the transmitting circuit is continuously supplied With signaling current to influence the cab indicator of any shifting locomotive in the yard RY, and the lamps Li and L2 at the respective control stations are continuously illuminated to indicate that the system is in working order.

An operator at the station SI Wishing to signal to the crew of a shifting locomotive in yard RY would depress the push button PBI to open contact I3 and deenergize the control relay RI, the release of relay R! being followed by the termination of the signaling current and the extinguishing of the cab indicator on such locomotive. As stated hereinbefore, extinguishing the cabindicator may be a signal to the crew of the shifting locomotive to stop. Release of the push button PBI by the operator at station SI would reestablish the display of the cab indicator. lt is clear that, by operating push button PBI for long and short intervals according to a prearlranged code to establish corresponding displays of the cab indicator, code signaling may be effected for governing the movement of the shifting locomotive.

When the push button PBI is depressed and contact I3 is opened, the lamps LI and L2 are both extinguished. The extinguishing of the lamp L2 at station S2 would indicate to the operator at station S2 that the operator at station` SI is signaling or that there is a failure of the system.

If the operator at station SI wishes to talk to the crew on the locomotive, he would depress the push button PBI and then talk into the microphone MI. Depressing the push button PBI closes a normally open contact I9 and completes a microphone circuit extending from the B battery terminal over normally closed contact 2l of push button PB2 at station S2, wire 22, contact I9 now closed, microphone MI, line wire 20, primary winding II of input transformer T2 and to the C terminal. The microphone circuit thus completed is effective tov modulate the carrier current generated in the modulator-oscillator MO with the voice frequencies produced by speaking into the microphone MI, with the result that the transmitting circuit is now supplied with a carrier telephone current which is picked up at the locomotive and the voice frequencies reproduced in the vehicle carried receiving apparatus in the manner described hereinbefore. The lamp LAI is supplied with current in parallel with microphone MI when the contact I9 is closed and is illuminated to indicate to the operator at station SI the effective condition of the microphone circuit. It is to be observed that the circuit for microphone Mi and lamp LAi can loe completed only when the push button PB2 at the station S2 is in the normal position and contact 2I thereof is closed. Thus, should the lamp LAI not light up when the push button PBI is depressed, the operator at station SI would know that his microphone is ineffective, due either to communication being in progress from the other control station or that there is a failure of the system. When the operator at station SI has completed signaling or telephoning to the crew of the locomotive, he would release the push button PBI and the normal condition of the system would at once be reestablished.

The operator at station S2 may signal to the crew of the locomotive by operation of the push button PB2 to control the relay RI, since the normally closed contact I5 of push button PB2 is interposed in the control circuit for relay RI The lamps LI and L2 are also responsive to operation of the push button PB2 in the same manner they respond to operation of the push button PBI. The operator at station S2, to initiate telephone communication, would depress the push button PB2 and then speak into the microphone M2. The push button PB2, when depressed, closes a normally open contact 23 and completes a circuit for the microphone M2, and which circuits extends from B battery terminal over normally closed con-- tact 24 of push button PBI, wire 22, contact 23 now closed, microphone M2, line wire 20, primary winding II of transformer T2 and to the C* terminal. Thus, operation of the push button PB2 not only deenergizes relay RI to discontinue the sending of the signaling current but renders the microphone M2 effective to modulate the carrier current, with the result that the transmitting circuit is supplied with a carrier telephone current having the voice frequencies produced by the operator at station S2 speaking into the microphone M2. The lamp LA2 is illuminated when contact 23 is closed and indicates to the operator at station S2 the effective condition of the microphone M2. Again, it is to be observed that the circuit for the microphone M2 and lamp LA2 at station S2 can be completed only if push 'button PBI is in the normal position and the Contact 24 thereof is closed. Hence, if the lamp LA2 fails to light up in response to operation of the push button PB2, the operator at station S2 would know that communication is in progress from the station Si or that the system, is inoperative. With such connection between the two control stations Si and S2, the undesirable confusion which might result, should transmission of instructions to the shifting locomotive be attempted from both stations simultaneously, is avoided. Furthermore, it is to be observed that when an operator at either station is transmitting speech the operator at the other station may depress his push button and terminate the conversation from the other station and set up a stop signal on the locomotive.

Apparatus constructed in the manner disclosed in Figs. 1 and 2 provides a communication system for railway yards that is based on the closed circuit principle and is simple and reliable.

Although I have herein shown and described only one form of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims Without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

i. A communication system for a railway yard, comprising a transmitting circuit which includes a track rail of each track of the yard for electrically transferring energy to a vehicle on any one of the tracks, transmitting apparatus coupled with said circuit and including a modulatoroscillator, circuit means connected with said transmitting apparatus and normally active to cause said modulator-oscillator to generate a predetermined signaling current for normally supplying the transmitting circuit with such signaling current, a control station including a microphone and a manually operable circuit controller, and other circuit means governed by said controller to render the first mentioned circuit means inactive and to connect said microphone with the transmitting apparatus for supplyingr a carrier telephone current to said transmitting circuit.

2. A communication system for a railway yard, comprising a transmitting circuit which includes a track rail of cach track of the yard for electrically transferring energy to a vehicle on any one of the tracks, transmitting apparatus coupled with said circuit and including a modulator-oscillator, circuit means connected with said transmitting apparatus and normally active to cause said modulator-oscillator to generate a predetermined signaling current for normally supplying the transmitting circuit with such signaling current, a control station including a microphone and a manually operable circuit controller, other circuit means governed by said controller to render the rst mentioned circuit means inactive and to connect said microphone with the transmitting apparatus for supplying a carrier telephone current to said transmitting circuit, and indication means including an indicator located at said control station and governed by said rst mentioned circuit means to indicate that said first mentioned circuit means is active.

3. A communication system for a railway yard, comprising a transmitting circuit which includes a track rail of each track of the yard for electrically transferring energy to a vehicle on any one of the tracks, transmitting apparatus coupled With said circuit and including a modulator-oscillator, circuit means connected with said transmitting apparatus and normally active to cause said modulator-oscillator to generate a predetermined signaling current for normally supplying the transmitting circuit with such signaling current, a plurality of control stations located at selected points about the yard, said stations each including a microphone and a manually operable circuit controller, means governed by the circuit controller of each station to render said circuit means inactive and to connect the associated inicrophone with the transmitting apparatus to supply a carrier telephone current to the transmitting circuit, and other means governed by each circuit controller to render the remaining circuit controllers each ineffective to connect its associated microphone to the transmitting apparatus.

4. A communication system for a railway yard, comprising a transmitting circuit which includes a track rail of each track of the yard for electrically transferring energy to a vehicle on any one of the tracks, transmitting apparatus coupled with said circuit and including a modulator-oscillator, circuit means connected with said transmitting apparatus and normally active to cause said modulator-oscillator to generate a predetermined signaling current for normally supplying the transmitting circuit with such signaling current, a plurality of control stations located at selected points about the yard, said stations each including a microphone and a manually operable circuit controller, means governed by the circuit controller of each station to render said circuit means inactive and to connect the associated microphone with the transmitting apparatus to supply a carrier telephone current to the transmitting circuit, other means governed by each circuit controller to render the remaining circuit controllers each ineffective to connect its associated microphone to the transmitting apparatus, a rst indication means governed by said circuit means and including an indicator at each control station to indicate at each station the active condition of said circuit means, and a second indication means governed by said controllers and including an indicator at each station to indicate when a microphone at one o1 the stations is made active.

5. A communication system for a railway yard, comprising a transmitting circuit which includes a track rail of each track of the yard for electrically transferring energy to a vehicle on any one of the tracks, transmitting apparatus coupled with said circuit and including a modulator-oscillator, circuit means connected with said transmitting apparatus and normally active to cause said modulator-oscillator to generate a predetermined signaling current for normally supplying the transmitting circuit with such signaling current, a plurality of control stations located at selected points about the yard, said stations each including a microphone and a manually operable circuit controller, means governed by the circuit controller of each station to render said circuit means inactive and to connect the associated microphone with the transmitting apparatus to supply a carrier telephone current ting circuit, other means governed by each circuit controller to render the remaining circuit controllers each ineiective to connect its associated microphone to the transmitting apparatus, a rst indication means governed by said circuit means and including an indicator at each control station to indicate at each station the active condition of said circuit means, and another indicator at each control station and connected in parallel with the associated microphone to indicate when the microphone is effective and when communication is in progress at another control station.

6. A communication system for a railway yard comprising, a transmitting circuit including a rail of each track of the yard for the transfer of energy to a vehicle on any one of the tracks, transmitting apparatus coupled with said circuit and including a source ci carrier current, a relay, circuit means including a contact of said relay and connected with said transmitting apparatus to supply the transmitting circuit with a signaling current which is equivalent to said carrier modulated by a predetermined frequency, a control station provided with a microphone and a circuit controller biased to a normal position, a rst circuit including a normally closed contact of said controller and a winding of said relay to energize the relay for normally supplying the transmitting circuit with said signaling current to check that the transmitting circuit is in working order, and a second circuit including a normally open contact of said controller and said microphone and connected with the transmitting apparatus to modulate said carrier with voice frequencies for supplying the transmitting circuit with a carrier telephone current.

7. A communication system for a railway yard comprising, a transmitting circuit including a rail of each track of the yard for the transfer of energy to a vehicle on any one of the tracks,

to the transmits rail of each track of the yard for the transmitting apparatus coupled with said circuit and including a source of carrier current, a relay, circuit means including a contact of said relay and connected with said transmitting apparatus to supply the transmitting circuit With a signaling current which is equivalent to said carrier modulated by a predetermined frequency, two control stations each provided with a microphone and a circuit controller biased to a normal position, a first circuit including a normally closed contact of each of said controllers and a Winding of said relay to energize the relay and condition the transmitting apparatus for normally supplying the transmitting circuit with said signaling current to check that the transmitting circuit is in Working order, and a second circuit means including a normally closed contact of each controller and a normally open contact of each controller as well as the microphones for connecting the microphone at the station at which the controller is operated with the transmitting apparatus to modulate the carrier With voice frequencies for supplying the transmitting circuit with a carrier telephone current and to render the remaining microphone inelective.

8. A communication system for a railway yard comprising, a transmitting circuit including a transfer of energy to a vehicle on any one of the tracks, transmitting apparatus coupled With said circuit and including va source ofY carrier current, a relay, circuit means including a contact of said relay and connected With said transmitting apparatus to supply the transmitting circuit with a signaling current which is equivalent to said carrier modulated by a predetermined irequenoy, two control stations'each provided with va microphone and a circuit controller biased to a normal position, a first circuit including a normally closed contact of each of said controllers and a winding of said relay to energize the relay and condition the transmitting -apparatus for normally supplying the transmitting circuit With said signaling current to check that the transmitting circuit is in working order, a second circuit including a normally closed contact of the controller at one station and a normally open contact of the controller at the other station as well as the microphone at said other station to connect the microphone with the transmitting apparatus, and a third circuit including a normally closed contact of the controller at said other station and a normally open contact of the controller at said one station vas well as the microphone at said one station to connect that microphone with the transmitting circuit, Whereby the signaling current is discontinued by the operation of either controller and telephone communication is effected from the station at which the controller is operated.

9. In combination with transmitting apparatus capable of modulating a carrier current with voice frequencies and of producing a signaling current equivalent to said carrier modulated at a predetermined frequency, a relay, circuit means including a contact of the relay to condition said transmitting apparatus to produce said signaling current, a first and a second control station spaced apart and each provided with a microphone and a manually operable circuit controller biased to a normal position, a rst circuit including a normally closed contact of each of said controllers and a Winding of the relay to energize said relay for normally conditioning the transmitting apparatus to produce said signaling current, a second circuit to connect the microphone of the first station to the transmitting apparatus and including a normally closed contact of the controller at said second station and a normally open contact of the controller at said rst station, and a third circuit to connect the microphone of the second station to the transmitting apparatus and including a normally closed contact of the controller at said iirst station and a normally open contact of the controller at said second station.

l0. In combination With transmitting apparatus capable of modulating a carrier current with voice frequencies and of producing a signaling current equivalent to said carrier modulated at a predetermined frequency, a relay, circuit means including a contact of the relay to condition said transmitting apparatus to produce said signaling current, a first and a second control station spaced apart and each provided with a microphone and a manually operable circuit controller biased to a normal position, a first circuit including a normally closed contact of each of said controllers and a winding of the relay tol energize said relay for normally conditioning the transmitting apparatus to produce said signaling current, a second circuit to connect the microphone of the first station to the transmitting apparatus and including a normally closed contact of the controller at said second station and a normally open contact of the controller at said rst station, a third circuit to connect the microphone of the second station to the transmitting apparatus and including a normally closed Contact of the controller at said first station and a normally open contact oi the controller at said second station, and an indication circuit including an indicator at each oi said stations and a front contact of said relay.

l1. In combination With transmitting apparatus capable of modulating a carrier current with voice frequencies and of producing a signaling current equivalent to said carrier modulated at a predetermined frequency, a relay, circuit means including a contact of the relay to condition said transmitting apparatus to produce said signaling current, a first and a second control station spaced apart and each provided with a microphone and a manually operable circuit controller biased to a normal position, a first circuit including a normally closed contact of each of said controllers and a Winding of the relay to energize said relay for normally conditioning the transmitting apparatus to produce said signaling current, a second circuit to connect the microphone of the first station to the transmitting apparatus and including a normally closed contact of the controller at said second station and a normally open contact of the controller at said iirst station, a third circuit to connect the microphone of the second station to the transmitting apparatus and including a normally closed contact of the controller at said first station and a normally open contact of the controller at said second station, an indication circuit including an indicator lampat each station and a front contact of said relay, and another indicator lamp at each station connected in multiple with the associated microphone.

12. In combination with transmitting apparatus capable of modulating a carrier current with voice frequencies to produce a carrier telephone current, a rst and a second control station spaced apart and each including a microphone and a manually operable circuit controller biased to a normal position, a rst circuit to connect the microphone at the rst station with the transmitting apparatus and including a normally closed contact of the controller at said second station and a normally open Contact of the controller at said rst station, a second circuit to connect the microphone at the second station with the transmitting apparatus and including a normally closed contact of the controller at said first station and a normally open contact of the controller at said second station, an indicator at the rst station governed by said rst circuit, and an indicator at said second station governed by said second circuit.

13. A communication system for a railway yard, comprising a normally closed transmitting circuit which includes in multiple a track rail of each track of the yard for transfer of energy to a vehicle on any one of the tracks, a Winding interposed in said circuit, a source of signaling current of a predetermined frequency, a control station including a microphone and a circuit oontroller, means including a normally closed contact of said controller to couple said source with said winding for normally supplying the transmitting circuit with such signaling current to check that the transmitting circuit is in Working order, and other means including a normally open contact of said controller to at times couple the microphone with said Winding for supplying a telephone current to said transmitting circult.

RALPH R. KEMMERER. 

